1. Field of the Invention
This invention relates in general to integrated circuits and more specifically to integrated circuits with one time programmable elements.
2. Description of the Related Art
One time programmable (OTP) elements such as fuses and PROM cells are utilized in integrated circuits for adjusting the circuitry after fabrication of an integrated circuit. For example, a programmable fuse may be used to adjust circuitry of an integrated circuit for specific conditions or correct for manufacturing defects.
One specific use of OTP elements is for providing repair information that controls the usage of redundant cells in replacing defective cells of a memory array. Another use is for tuning analog circuitry by trimming a capacitive or resistive value of an analog circuit or enabling and disabling portions of the system. A recent trend is that the same product is likely to be manufactured in different fabrication facilities though in a common process technology. Despite best engineering efforts, it is likely that each facility will have a slightly different process. Usage of OTP elements allows independent optimization of the product functionality for each manufacturing facility.
As integrated circuit technology advances, integrated circuit features (e.g. transistor gate length) have been decreasing, thereby allowing for more circuitry to be implemented in an integrated circuit. One challenge with implementing OTP elements such as a fuse in an integrated circuit is that fuse size reduction has not advanced at nearly the same rate as the reduction in size of transistor features. Accordingly, fuses may require a greater relative portion of the integrated circuit as integrated circuit technology advances.
In some integrated circuits utilizing OTP elements, different circuits each include dedicated OTP elements for providing redundancy repair information to a memory array and for providing non redundancy information for non memory array circuits e.g. for trimming, tuning, and/or timing adjustments. For example, each configurable circuit of an analog circuit would include its own OTP elements for providing the ability to program that feature. Such a system requires that an integrated circuit include a greater total number of OTP elements than may be needed.
What is desired is an improved technique for implementing OTP elements in an integrated circuit including both memory array circuits and non memory array circuits. In addition, it is desired that a unified approach be used for implementing OTP element solutions for multiple classes of circuits including memory array circuits and non memory array circuits.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted. The Figures are not necessarily drawn to scale.